Despite having the 3ivx codec installed (and several others in an attempt to identify the problem) we are still getting only video without audio for our mp4 in MediaLab with no accompanying error message. QuickTime and VideoLan play the mp4 fin (with sound), but Windows Media Player also does not play the sound and gives the error message "unable to download an appropriate decompressor." The "enhahanced video" toggle in MediaLab seems to make no difference. We have tried uninstall/reinstall of several different codecs, including multiple reboots between each attempt.

I'm assuming since MediaLab uses WMP and the video works on the players that the problem is with MediaLab or WMP settings. Any idea where to look next?